This invention relates to a composition and process for the treatment of patients afflicted with renal calculi (kidney stones). More particularly, this invention is directed to a sterile solution adapted for in vivo dissolution of struvite kidney stones.
Renal calculi represent a difficult therapeutic challenge. Even with the dramatic changes which have occurred in the management of upper urinary tract calculi with the introduction of extracorporeal shock wave lithotripsy (ESWL) and the popularization of percutaneous nephrostolithotomy (PCNL), patients receiving treatment by such procedures still are known to retain stone fragments which can lead to new kidney stone growth. To help clear the upper urinary tract of such potentially troublesome fragments, there has been renewed interest in chemolysis, that is the chemical dissolution of kidney stones in vivo with sterile chemolytic solutions.
Historically, chemolysis of renal calculi is one of the oldest forms of kidney stone therapy. Early chemolysis by citrate based compositions initially suggested great promise using retrograde catheters, but results obtained were found to be not comparable with surgical techniques. Calculi recurrence rates were high and consequently interest in that method of treatment declined. The initially developed chemolytic formulation and later modifications thereof still enjoyed limited applicability because of required long hospitalization and toxic side effects. While a few new chemolytic agents have been proposed over the past twenty years, only one composition, hemiacidrin, sold by the Guardian Chemical Company under the name Renacidin.RTM., has enjoyed significant medical use. The Renacidin.RTM. brand composition is a sterile aqueous solution containing 4% citric acid, 1% D-gluconic acid buffered with sodium carbonate and magnesium carbonate. Hemiacidrin thus comprises citric acid and D-gluconic acid in a 4 to 1 weight ratio with buffering amounts of sodium carbonate and magnesium carbonate. Routinely, hemiacidrin is utilized at concentrations from about 2.5% to about 15% in sterile aqueous solutions for clinical use following percutaneous stone procedures for irrigation of the remaining small fragments. A 5% hemiacidrin solution contains 2.8% citric acid with the final pH 3.9. A 10% hemiacidrin solution contains 5.6% citric acid with pH 3.6, close to the commerically available Renacidin.RTM. formulation.
This invention provides for a chemolytic solution for irrigation and in vivo dissolution of kidney stones, particularly struvite kidney stones. The solution exhibits stone dissolution characteristics far superior to those chemolytic solutions presently available. It has been found that by controlling citric concentration, and pH, and by use of pharmacologically acceptable chelating agents above specified threshold concentrations provides a superior formulation for in vivo calculi chemolysis.
It is therefore one object of this invention to provide an improved composition for in vivo dissolution of struvite calculi.
It is another object of this invention to provide an improved method for treatment of kidney stones utilizing a novel renal irrigant.
It is still another object of this invention to provide a novel chemolytic agent which can be used effectively alone or in combination with extracorporeal shock wave lithotripsy or percutaneous nephrostolithotomy.